Okay I'll put as much as I remember...
Spike and Buffy live together, but Spike doesn't let Buffy do anything he gets angry a lot and at one point when she tries to leave him he attacks her.
His father Giles is charge of the company he works for and recommends if Spike wants Buffy to marry him he should get her pregnant. so Spike changes Buffy's bc pill for placebos. finally Buffy does leave him and leaves spike a note on their coffee table.
Thats about all I remember off the top of my head hopefully someone can help I've been looking for this story for months

it's great...